The Lab12 PA Subwoofer Smack Down/Death Match - diyAudio
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Old 29th January 2014, 04:02 PM   #1
DHAA is offline DHAA  United States
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Default The Lab12 PA Subwoofer Smack Down/Death Match

The Eminence Lab12 has proven itself worthy in a variety of low-tuned PA applications. This venerable driver has held up well and is still a good candidate for many types subwoofer designs.

The Lab12 has been been around for a while and had been used in bass reflex, tapped horn, and front loaded horn alignments, so I propose a shoot-out of some of these Lab12 designs. Let's not get nasty. What is ideal for one person might not work for another, so please keep an open mind.

One of DIYaudio.com's elder statesmen, weltersys, has two proven designs that I submit for the first-round smack down.



In one corner we have the weltersys Keystone Sub, a tapped horn that is very adaptable:

Keystone Sub Using 18,15,&12 Inch Speakers

They Keystone Sub is a big fella (45" tall x 26.5" wide x 22.5" deep), but loaded with two Lab12's goes low and LOUD. This is the grey race on the graph below.




In the other corner we have the weltersys Dual Lab12 bass reflex design:

FREE SUB PLAN: Dual Lab12 (Front Loaded) by Welter Systems

The Dual Lab12 is tiny little fella (22.5" high x 26.5" wide x 22.5" deep) - half the size of the Keystone Sub. It goes just as low as the Keystone, but not as loud. This is the blue trace on the graph below.




So, if you needed a subwoofer that went really low and load, which of these designs would you build, and WHY? What are the pro's/con's you see of each design.

Let's keep things civil. I personally think these are both excellent designs - one of my biggest arguments would be size and portability.
Attached Images
File Type: png WelterSys Keytone Sub.png (271.1 KB, 605 views)
File Type: jpg WelterSys Dual Lab12 Sub.jpg (97.8 KB, 595 views)
File Type: png WelterSys Lab12.png (70.4 KB, 594 views)
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Old 29th January 2014, 05:57 PM   #2
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Another shape option with similar LF would be MSGR's:

$325 Lab 12 based PA tapped horn. ~35hz extension

The Keystone could be split in half vertically and occupy the same volume as the BR, so the size and portability option is there.
A single 12 also could be folded in to the BR shape, though would loose a little volume as it would need more folds than the Keystone or IPal design.

With a single driver TH cabinet having similar LF output, and more upper level than the dual ported using twice the power, the only thing the ported cabinet has going for it is it may not need the tops delayed to time/phase align a system, while the TH need tops typically delayed around 7ms.

Since almost any DSP has delay options, that difference would only apply to those using analog crossovers.

The BR can also be used with a single cone if you like a "haystack" LF response, the comparison at the same drive level between the single and dual load below. The single has almost the same output at 40 Hz as the dual, but has 6 dB less headroom in the upper "kick" region.

If anyone wants a pair of the WS BR cabinets, PM me.

Art
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File Type: png Lab12 1&2.png (106.3 KB, 573 views)

Last edited by weltersys; 29th January 2014 at 06:04 PM.
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Old 29th January 2014, 06:25 PM   #3
DHAA is offline DHAA  United States
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Quote:
Originally Posted by weltersys View Post
Another shape option with similar LF would be MSGR's:$325 Lab 12 based PA tapped horn. ~35hz extension

- The Keystone could be split in half vertically . . .

- A single 12 also could be folded in to the BR shape . . .

- With a single driver TH cabinet having similar LF output, and more upper level than the dual ported using twice the power . . .

- The BR can also be used with a single cone if you like a "haystack" LF response . . .
Art, some good points there in support of both designs. From my angle it looks like they both got some good punches in, but the Keystone is looking a bit stronger. Personally, I am favoring the single-width Keystone as my choice, unless someone can convince me otherwise.

And yes, I am familiar with MSGR's Lab12 design, it will entering the ring in a future battle. I actually have quite a few contenders lined up to get in the ring. Thanks for you comments.
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Old 29th January 2014, 09:26 PM   #4
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I think we need some "rules" for this battle.

For example:

1. Sim'd F3 should not be more than 40 Hz
2. Sim'd sensitivity efficiency @40 Hz should not be less than 96dB/2.83V/1M
3. Bandwidth must extend up to at least 100 Hz, -3dB

FWIW, I looked at the LAB12 as a possible TH candidate some time ago, but I found Fs a bit too low (I think TD suggested that for best results the Fs should be some way within the passband, suggesting that for a 40 Hz TH you should be looking for drivers with Fs around 50 Hz...)
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Old 29th January 2014, 10:07 PM   #5
tb46 is offline tb46  United States
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Hi DHAA,

Just a quick question: how do you suggest we compare a design to the keystone sub? I still maintain, that the Keystone sub cannot be simulated in Hornresp. I like Art's contributions of measurements, etc. a lot, but I can't compare them to Hornresp simulations that have not been build and measured (preferably by Art)

Regards,
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Old 30th January 2014, 01:23 AM   #6
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^exactly a true shoot out should be done the way traditional sub shoot outs are. Controlled environment (well same exact test conditions and location, same test mic etc) and unbiased data recorded.

I only have a minidsp umik. It has yet to be calibrated by CSL, but eventually I'll get around to it and take more measurements of my PAL12.
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Old 30th January 2014, 01:53 AM   #7
DHAA is offline DHAA  United States
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Mr. Steele, tb46, and MrgSr - thanks for you comments. I realize this will not be a completely fair way to compare the various designs, as a side-by-side test would be virtually impossible. What I am interested in is a discussion of the pro's/con's of each, and why someone would choose a particular one over another.

If Art has accurate measurements but no HR sim, then that is what we judge it on. If mRgSr has a decent HR sim, but possibly flawed measurements, then that is what we judge it on. I think most of you know enough about speaker design to make a fairly accurate judgement with the facts your are presented with.

A mobile DJ may have a bias for smaller BR cabs. A fixed install club owner might prefer a mega horn. I would like to hear people rationalize their choices.

I think my title "Smack Down/Death Match" might have been a little too drastic. My sons have been addicted to MMA lately and I think it has rubbed off on me a bit. I don't want this to turn into a nasty slugfest - I would hope everyone would be respectful of others needs and opinions. I would just like to hear others thoughts on these various designs.

When Art mentioned cutting his Keystone in half to increase portability, I truly had not considered that, and that is a definite bonus for me. I am sure there are many points that I and others have not considered, so let's hear them.

Mr. Steele, the guidelines you mentioned are fine with me - they all sound pretty reasonable. But if something is just a hair off of that, I say let it slide. Maybe just ding it a bit for whatever deficiencies it has and see if it has some other aspects that can make up for it?
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Old 30th January 2014, 01:54 AM   #8
sine143 is offline sine143  United States
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DHAA, I believe what they are refering to regarding the keystone is the fact that the vertical scale of arts measurements can not be directly compared to any of the other designs (other than those measured the same day by art that is).
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Old 30th January 2014, 01:56 AM   #9
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Okay I get it.

I don't think the HR sim on the PAL12 is more accurate than my measurements. But that's just a hunch.
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Old 30th January 2014, 01:58 AM   #10
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Don't forget Art's domino FLH. It seems to meet the criteria.
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